A recent study has found that “online interest in sex” peaks during the holidays with births spiking nine months later.

The finding suggests that significant increases in pregnancies are not wholly rooted in biology and could be more closely linked to society.

Researchers from the Instituto Gulbenkian de Ciência in Portugal and Indiana University poured over Internet searches and Twitter activity in 130 countries, using sex-related words as filters.

“The analysis revealed that interest in sex peaks significantly during major cultural or religious celebrations,” according to a press release from Indiana University. “These peaks broadly corresponded to an increase in births nine months later in countries with available birth-rate data.”

That correlation crossed cultures and was observed during Christmas in largely Christian nations and Eid al-Fitr, the end of Ramadan celebration, in Muslim countries.

“We observe that Christmas and Eid al-Fitr are characterized by distinct collective moods that correlate with increased fertility,” Luis Rocha, one of the researchers, said. “Perhaps people feel a greater motivation to grow their families during holidays when the emphasis is on love and gift-giving to children.”